1. Field of the Invention
The present invention relates to a coating apparatus and coating method for coating a substrate with a coating liquid, and more particularly relates to a coating method that is suitable for use in the application of developing solutions that remove undesired portions of the exposed film following exposure in photolithographic processes.
2. Description of Related Art
Among various types of LSI manufacturing processes, xe2x80x9cphotolithographic processesxe2x80x9d are generally processes in which a desired circuit pattern is exposed (exposure process) by means of an exposure apparatus such as a reduction projection exposure apparatus or scanning type reduction projection exposure apparatus on a photosensitive resin material (hereafter referred to as a xe2x80x9cresistxe2x80x9d) that has been applied as a coating to the surface of semiconductor substrate (hereafter referred to as a xe2x80x9cwaferxe2x80x9d) by means of a resist coating apparatus, after which the exposed portions or unexposed portions are dissolved and removed (developing process), so that a positive type or negative type resist pattern is formed.
One example of a developing apparatus current used in such developing processes is a developing apparatus manufactured by Tokyo Electron K.K. E2 type developing nozzles are mounted in this developing apparatus. An outline of these E2 type developing nozzles will be described below.
For example, such E2 type developing nozzles have a construction in which a plurality of nozzles are installed side by side in a straight line above a disk-form wafer in positions corresponding to the diameter of this wafer. Furthermore, a developing solution is discharged as a coating liquid from the respective nozzles while the wafer is caused to rotate by xc2xd rotation (180xc2x0) at an arbitrary rpm, so that the entire surface of the wafer is covered by this developing solution. Afterward, the developing solution is held on the wafer for a specified developing time with the wafer in a stationary state, and the desired resist pattern is then obtained by successively performing a pure water rinsing step and a spin-drying step.
Furthermore, other developing apparatuses include developing apparatuses equipped with scanning type developing nozzles (developing apparatuses manufactured by Tokyo Electron K.K. and Dai-Nippon Screen Seizo K.K.). An outline of such scanning type nozzles will be described below.
In the case of scanning type developing nozzles, a construction is used in which a plurality of nozzles are provided side by side in a straight line for a length corresponding to the diameter of the disk-form wafer. Furthermore, after the nozzles are provided on the outside of the wafer, a developing solution is applied as a coating to the surface of the wafer from the respective nozzles while the nozzles are caused to perform a parallel movement (scan) over the surface of the stationary wafer, so that the entire surface of the wafer is covered by the developing solution.
Furthermore, in all of the developing apparatuses, commercially marketed products with the commercial names of NMD-3, NMD-W and the like (manufactured by Tokyo Oka Kogyo K.K.) are used as developing solutions.
In recent years, as the demand for dimensional precision in resist patterns has increased due to the increasing fineness and increasingly higher degree of integration of LSI, there has been a demand for a reduction in the amount of waste liquid discharged in LSI manufacturing processes, e.g., a reduction in the amount of waste developing solution in the developing processes, out of consideration for the environment.
It is an object of the present invention to provide a coating method which make it possible to apply a coating liquid with a uniform film thickness to a region being coated, such as the surface of a wafer or the like, and which also make it possible to reduce the amount of coating liquid used compared to conventional techniques.
According to one aspect of the present invention, there is provided a coating method for a coating liquid comprising the steps of: preparing a coating surface which has a plurality of regions that are to be coated with a coating liquid; providing a plurality of storage chambers under atmospheric pressure in which the coating liquid is stored in respective amounts that enable the coating surfaces of a corresponding regions being coated to be coated to substantially the same coating thickness; disposing the corresponding regions being coated on the undersides of the storage chambers; and applying the coating liquid on the coating surfaces of the regions being coated by pushing the coating liquid stored in the storage chambers by the atmospheric pressure.
According to the coating method of the present invention, since the amounts of coating liquid per unit area that are simultaneously supplied to the respective regions being coated are set as identical amounts, the coating liquid can be applied without causing any bias within the regions being coated in terms of the amount of coating liquid supplied to the regions being coated. Accordingly, the uniformity of the film thickness of the coating liquid that is formed on the regions being coated can be improved.
Furthermore, according to the coating method of the present invention, excessive supply of the coating liquid to the regions being coated can be suppressed, so that the amount of coating liquid used can be reduced compared to conventional techniques. Specifically, the amount of waste coating liquid generated in conventional techniques can be reduced.